It sounds like it may be a fungus (ovularia, ramularia, cercospora)
affecting the lilypads, pinching off all affected leaves usually
clears it up

Regards, andy
http://www.members.aol.com/abdavisnc/swglist.html


I have a newish pond - it's been filled for about two months. The
water lilies I have bought have suffered from major discolouration of
the leaves within a week or so of putting them into the pond.
Basically the leaves start going brown in patches until they are
completely brown. I can't see anything obvious like larvae. Also,
and maybe connected, the leaves are getting rather ragged at the
edges.

Any ideas?